Constrained Physical Database Design - Automated Physical Database Design and Tuning - page 214

6

5

4

3

2

400 500 600 700 800

Expected Cost

900 1000 1100

FIGURE 11.8 Nondominated configurations for relaxed S70 .

the reason for the original specification resulting in no solutions is that the
smallest such configuration requires 2.4 GB.
Suppose that we pick this smallest configuration in Figure 11.8 (after all,
our initial hard constraint limited the storage to 2 GB). Figure 11.9 contrasts
the execution cost of the queries in the workload under both this configuration
and the one obtained when optimizing only for storage (i.e., when dropping
the S70 constraint) but giving the 2.4 GB storage bound that the S70 config-
uration required. Each query in the figure is associated with a light bar that
represents 70% of the cost of the query under the base configuration (i.e., the
baseline under the S70 constraint). Additionally, each query in the figure is
associated with a narrower black/white bar, whose extremes mark the cost of
the query under the configuration obtained with just a storage constraint and
the configuration obtained by additionally enforcing S70 . If the configuration
obtained with S70 is the cheaper one, the bar is painted black; otherwise, it

300

250

200

150

100

50

0

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Queries

12 13 14 15 16 17 18 19 20 21 22

FIGURE 11.9 Expected query costs for S70 .